What is Polished Concrete?
That question has plagued the concrete polishing industry for several years. Recently, the Concrete Polishing Association of America (CPAA), a trade association comprised of leaders from all aspects of the concrete polishing industry, has taken a huge step to providing a solid answer to that question and bringing stability to the industry.
The concrete polishing industry is still quite young. Especially when compared to other flooring systems or floor coverings - most of which have been around for several decades. As with most young industries, there is bound to be a certain amount of confusion surrounding the new technology and artisans crafting out a new trade. Concrete polishing is not different.
In the beginning...
Polished concrete was introduced into the United States by distributors, manufacturers, and contractors who polished natural stone. The goal was to create a mirror like finish through the use of bonded abrasives. It wasn't long before some manufacturers and contractors offered cheaper, faster ways to create a similar looking product that couldn't possibly offer the same aesthetics or performance. This obviously created massive confusion in the industry. Architects, trying to offer their clients a high performance flooring system, specified polished concrete and were often given simply a “shiny” floor. With no way of making a distinction between the good and bad processes, confusion and mistrust ascended to an even higher level. Architects began to traverse back to traditional floor covering and coatings, not because of higher performance, but simply more for consistent and predictable aesthetics. Adding to all of this mayhem was a retail market transitioning away from high end appearances (at least for the flooring) and moving more toward modern, industrial looks. Many of these retailers were aware of the lesser performance of lower cost versions of “polished concrete”. Even still, the “polished concrete” flooring could easily be justified since routine maintenance and occasional renovation was less than traditional floor coverings or coatings. Many consumers were not aware of the compromises made by the retail markets and requested higher quality aesthetics and performance for the cheaper prices demanded by the larger, competitive retail market. This, coupled with the fact that contractors were (are) fighting for market shares within the industry instead of selling against other flooring systems, has led to what some have perceived to be an all-time low for our industry.
The future of polished concrete
With all of this happening in the background, the concrete polishing industry has continued to grow and show tremendous outlook for the future. Especially in what has been arguably a stagnant economy. So how do we support this growth and preserve an industry that has great potential? Simply by restoring the consumer's faith in the product. One step in that direction would be to create a vocabulary that architects, consumers and contractors could communicate effectively for the expectations of the end product. As you can imagine, this effort created its own set of challenges with varying opinions surrounding “shiny floors.”
From the inception of the CPAA, committees were created to address organizational issues as well as industry needs. One of these is the Standards Committee, which is comprised of a diverse cross section of leaders with a common goal and desire to see our industry grow. These individuals represent key areas of our industry - construction, manufacturing, and architectural. Therefore, as documents are created, they are born from a consensus of vast ideology of the concrete polishing industry. This brings us back to the earlier statement that the CPAA has taken a huge step toward offering an answer to “what is polished concrete?”
Language that makes sense
The CPAA recently announced to the industry an extensive list of definitions. This terminology will allow architects and general contractors to better communicate with polishing technicians. As previously stated, by gaining a clearer line of communication a more predictable end product can be achieved, thereby restoring the design community's faith in polished concrete. Before we discuss the definitions, it must be understood that producing polished concrete is truly unique in nature.
Most flooring products are manufactured in a controlled environment and transported to the job site for installation. Even polished concrete's distant cousin, terrazzo, utilizes standardized aggregates and colored matrixes installed by the technician for a more controlled installation process. Polished concrete on the other hand is produced, manufactured in a sense, directly at the job site. As such, the polishing technician is faced with a different set of variables that are subjective to each project. It has been said that, when processing concrete to a polished finish, “there are multiple ways to skin this cat.”
The polishing technician must have the knowledge to recognize the variables faced at the job site, and then have the leeway within the specifications to adjust to those demands. The polishing technician must also be held accountable for his craftsmanship and the end product. The CPAA offers a viable solution by creating clear, measurable benchmarks that the polishing technician must meet for each classification of polished concrete.
According to the CPAA, polished concrete is defined as “the act of changing a concrete floor surface, with or without aggregate exposure, to achieve a specified level of gloss using one of the listed classifications: Bonded Abrasive Polished Concrete, Burnished Polished Concrete, or Hybrid Polished Concrete.”
Bonded Abrasive Polished Concrete, the most sought after and misunderstood process, is defined as the multi-step operation of mechanically grinding, honing, and polishing a concrete floor surface with bonded abrasives to cut a concrete floor surface and to refine each cut to the maximum potential to achieve a specified level of finished gloss as defined by the CPAA.
Burnished Polished Concrete is a common process used in the retail market. The multi-step operation of mechanical friction-rubbing a concrete floor surface with or without waxes or resins to achieve a specified level of finished gloss as defined by the CPAA. In most cases, the facility receiving this process has really, really good concrete that doesn't require much improvement to meet the customer's expectations for aesthetics or performance.
Hybrid Polished Concrete, another version of polished concrete, combines the two processes described above. This process is defined as a multi-step operation, using either standard grinding / polishing equipment, lightweight equipment, high speed burnishing equipment, or a combination of, to combine the mechanical grinding, honing, and polishing process with the friction rubbing process by utilizing bonded abrasives, abrasive pads, or a combination of, to achieve the specified level of finished gloss as defined by the CPAA.
Film Coating is the final way of creating a “shiny floor.” Although this application does not meet the CPAA's standards for polished concrete, the requirement of chemical resistance or small, low traffic areas may be some of the factors that dictate its use.
So which one is best? Which one offers the best performance at the lowest cost? That depends on the type of facility, intended aesthetic appearance, and projected amount of use and maintenance. Therefore, the CPAA offers a guideline as to the expectation of performance based on some common factors.
So, what the heck is “shiny?”
Notice that all processes are required to meet the “specified level of gloss as defined by the CPAA.” This is a very important aspect, because “shiny” is viewed, and measured in many ways. The CPAA has stated that a gloss measurement is comprised of multiple values.
A Gloss Measurement is a determination of specular gloss that incorporates distinction of image, haze and Rspec. Gloss, specifically specular gloss, is a measurement of the quantity of light reflected from the surface, or simply how reflective a surface is. Distinction of Image (DOI) is the quality of light reflected from the surface, or how clear an object appears in the reflection of the surface. Haze is a measurement that offers a value of the “halo” effect surrounding a reflection. Rspec is the measurement of the peak gloss value over a very narrow angle. Rspec values are subjective to a flat, or refined, surface.
By combining these measurements, and setting minimum limits for varying degrees of a finished floor, the polishing technician is held to a higher standard of performance. For instance, a Level 3 Finished Gloss requires a minimum sheen (specular gloss) value of 35GU and a minimum DOI value of 65. Level 4 Finished Gloss levels raise the bar higher with minimum sheen value of 50GU and minimum DOI value of 85. All measurements are required to be taken before the application of a stain protective product, commonly referred to as guards.
In order to meet the requirements of a Level 3 or Level 4 Finished Gloss value, the polishing technician must be knowledgeable and skilled enough to recognize the variables within the concrete (and job site conditions) and adjust accordingly, through processes and diamond tool selection, to properly refine the concrete. If the concrete is properly refined to meet the specified requirements, regardless of which process is used, the technician has provided the customer with an end product that has decisive values for aesthetics and performance. Even meeting the requirements of lower levels of specified gloss will give the consumer better looking and higher performance floors than what has mostly been offered in the past.
Know your limitations
The polishing technician must also be aware of the limitations of the different classifications of polished concrete. A Burnished Polished Concrete process cannot be used to provide the customer Class D (large) exposed aggregate and cannot provide a Level 3 or Level 4 Finished Gloss. Likewise, the Hybrid Polished Concrete process has its own limitations. The Hybrid Polished Concrete process, utilizing bonded abrasives, can refine the substrate to some degree, but when used entirely with light weight equipment will not provide a finish with the longevity compared to a Bonded Abrasive Polished Concrete process. Only through a very thorough understanding of the polishing process itself will the polishing professional be able to discern the most economical and most thorough means to meet the demands of the specifier.
The demands of higher performance will not only help the design community and consumer, but ultimately will allow contractors to better estimate time and materials required to produce the end result. Hopefully, this will shift the focus toward providing a competitive bid, yet market against other floor coatings and coverings rather than other contractors.
I would like to go on record here stating that this is by far not the final step toward unifying our industry. The CPAA Standards Committee is diligently working to update specifications and additional test methods to further define the different processes. The CPAA is also working with other trade associations to establish better guidelines for concrete and concrete placement / finishing techniques that will ultimately offer better polished concrete. Polished concrete offers many advantages over traditional floor covering and coatings. So many advantages in fact, that it is imperative that we all work together for its success for the good of everyone.
A complete list of the definitions, position papers, guidelines and specsifications, can be found on the CPAA's website:
© 2013 L&M Construction Chemicals, Inc. | ConcreteNews Spring 2013.